Method for traversing a workpiece with a working head

ABSTRACT

In order to apply work uniformly along a line which changes direction at a corner, the working head is moved radially toward and away from the corner simultaneously with its being rotated into, across and past the corner, keeping the working head uniformly directed at the workpiece. The method is applicable to automated welding during shipbuilding, and to like tasks.

United States Patent 1191 Adachi et al.

Filed: Jan. 8, 1974 Appl. N0.: 431,722

[73] Assignee:

[30] Foreign Application Priority Data Feb. 2, 1973 Japan 48-12856 US. Cl. 29/470, 219/125 R int. Cl. B23k 29/00 Field of Search 29/470, 471.]; 228/8, 9, 228/25, 32; 219/125 R, 125 PL, 126; 180/79, 79.1; 318/578 [5 6] References Cited UNITED STATES PATENTS 1,983,321 12/1934 Stephens et a1 219/125 R Mar. 18, 1975 2,427,696 9/1947 Trombetta 2211/32 x 3,469,068 9/1969 Wall, 11 219/125 R 3,740,526 6/1973 111616611 61 Z11. 219/125 R x 3,764,777 10/1973 5611666 6161 219/125 R 3,781,510 12/1973 P161112 6161. 219/125 R Primary E.\'aminerAl Lawrence Smith Assistant E.\'aminer-K. J. Ramsey Attorney, Agent, or Firm-Cushman, Darby & Cushman [57] ABSTRACT In order to apply work uniformly along a line which changes direction at a corner, the working head is moved radially toward and away from the corner simultaneously with its being rotated into, across and past the corner, keeping the working head uniformly directed at the workpiece. The method is applicable to automated welding during shipbuilding, and to like tasks.

1 Claim, 11 Drawing Figures PATENTEUHAR 1 8191s HEET u, E

FIGQ

PATENIEDMARI ems snmsi g FIG.II

l METHOD FOR TRAVERSING A WORKPIECE WITH A WORKING HEAD BACKGROUND OF THE INVENTION In steel constructions such as, for example, a hull of a steel ship, there are many component structures and almost all of these structures are fabricated by welding. More particularly, with reference to FIG. 1 of the drawings, it is typically necessary 'not only to weld along an edge line from point a to point b but also a weld continuously along an edge line b-c intersecting at a right angle with said first edge line a-b. In addition to the welding work, various other tasks such as inspection, surface finishing, cleaning, painting, and the like are often required to be carried out along these edge lines.

An automatic welding apparatus which can carry out such linear welding is disclosed in Japanese Patent Publication No. 154lO/197l. However, in case of this known apparatus, in order to conduct the welding from one corner to another corner it is necessary to displace a welding torch within the welding apparatus, and as a result, the structure of the apparatus is complexed, the weight is increased, and difficulties occur frequently. Furthermore,-when it is desired to weld along the edge line bc which intersects at a right angle with the previously welded edge line a-b, the entire apparatus must be displaced for resetting, and if there exist protrusions d as illustrated in FIG. I, sometimes it is impossible to continue welding up to the terminal end within the construction.

There are many occasions where ship components or the like are fabricated by welding lattice-like cross-laid ribs to a plate as stiffening means therefor. Within each lattice cell, the ribs are welded at their base to the plate, a smooth welding fillet being much sought after. Beside the welding work, inspection, surface finishing, cleaning and the like need to be carried out at the same work sites.

SUMMARY OF THE INVENTION The present invention relates to improvements in an automatic process of working such as, for example, welding, inspection, surface finishing, cleaning, painting, etc., that is free from the aforementioned disadvantages, and the invention is characterized in that upon working along work lines intersecting at a predetermined angle with each other, at a corner portion where said work lines intersect with each other, a working head is moved in a radial direction while it is rotated, whereby a work may be carried out continuously from one of said work lines to the other work line intersecting therewith.

It is an object of the present invention to provide an automatic process of working in which said working can be efficiently conducted continuously from one of work lines to the other work line intersecting at a pre determined angle with the former without being interrupted.

As described above, since the present invention is characterized in that, upon working along work lines intersecting at a predetermined angle with each other at a corner portion where said work lines intersect with each other a working head is moved in a radial direction while it is rotated, it is possible that after the tip end of the working head has been moved to the corner portion along one ofthe work lines while being maintained in a predetermined positional relationship to said one work line, to continuously move the tip end of the working head to the corner portion of the other work line intersecting at a predetermined angle with said one work line, and further to move said tip end of the working head along the other work line while maintaining the working head in a predetermined positional relationship to the other work line. Thereby, horizontal fillet welding along work lines intersecting with each other can be performed continuously and efficiently.

In addition, since the working head is moved in a radial direction while it is rotated according to the present invention, even if there exist protrusions on the body to be worked, said working can be conducted smoothly without being obstructed by the protrusions.

Still further, since the present invention is applicable not only to a working system having a single working head but also'to a working system having two or more working heads, it is possible to efficiently conduct two or more kinds of working simultaneously.

The principles of the invention will be further hereinafter discussed with reference to the drawings wherein preferred embodiments are shown. The specifics illustrated in the drawings are intended to exemplify, rather than limit, aspects of the invention as defined in the claims.

BRIEF DESCRIPTION OF THE DRAWING In the Drawings FIG. 1 is a perspective view of a typical workpiece to be fabricated or otherwise worked upon by the method described herein;

FIG. 2 is a schematic, fragmentary plan view of the workpiece showing work being applied thereto by this method;

FIG. 3 is a schematic, fragmentary cross-sectional view on line IIIIII of FIG. 2;

FIG. 4 is a perspective view of a typical lattice-like ship component including cross-laid ribs to be welded to a plate in accordance with the invention;

FIG. 5 is a plan view of apparatus for performing the method described in respect to FIGS. 1-3 on a compo nent as is illustrated in FIG. 4;

FIG. 6 is a longitudinal cross-sectional view taken along line VV of FIG. 5;

FIG. 7 is a diagrammatic, fragmentary plan view, similar to FIG. 2, of a mode of operation of the apparatus of FIG. 5;

FIG. 8 is a schematic plan view of one complete lattice cell showing the progress of the apparatus of FIG. 5 thereabout as the method is performed;

FIGS. 9, 10 and 11 are views respectively comparing to FIGS. 5, 6 and 7, but of a modified form of apparatUS.

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS OF THE INVENTION The Method Referring to FIGS. 2 and 3, reference numeral 12 designates a welding torch e.g., of solid wire type, and the welding conditions for the torch 12 are typically preselected at awire diameter of 1.6 mm, a welding current of 450A, a welding voltage of 42 43V, a wire directed position of I 1.5 2 mm (see FIG. 3), and a welding speed 'of 800 mm/sec (in case of a leg length of 5 mm).

Reference numeral 4 designates a workpiece comprising a bottom plate 5 and a lattice form of side plates 6 which stand at a right angle to the bottom plate 5 and intersect at a right angle with each other, in which a welding line 16 where the bottom plate 5 and the side plate 6 intersect with each other, intersects at a right angle with another welding line 16 within a horizontal plane as illustrated in FIG. 2.

Reference numeral 22 designates a locus of a pivotal position for the torch 12, which is spaced from said welding line 16 at a predetermined distance in parallel thereto.

Reference symbol 6,, represents the angle formed between a straight line connecting a cross point 22A between adjacent loci 22 of a pivotal position and another cross point l6I between adjacent welding lines 16-and the welding lines 16. This angle is equal to 45 in the illustrated case, since the angle formed between the adjacent welding lines 16 is a right angle.

In addition, reference symbol 0, represents the angle formed between the radial movement lines 161 22A, 1611 22A, 16III- 22A, l6IV 22B, 16V 22C, 16V] 22C, l6VII 22C, 16VIII 22 D and the axis of the welding torch 12. In this example, angle (9 is preset at 0 Reference symbol 0 represents the angle formed between the axis of the welding torch 12 positioned in the rectilinear movement section l6lII to 16V and the normals to the welding line 16. In this example, angle 0 is preset at 0 Still further, reference symbol 6;, represents the rotational angle of the radial movement lines 16I e 22A to be carried out over the welding region 16V to 16V! l6lII 22A of the welding torch from the corner l6l of the welding line 16 up to the rectilinear movement section l6lII 16V, and from the aforementioned definition and preset values it is obvious that the angle 6 takes the value of 0 9O-0 6 0 10 5 Reference symbol 0, represents the rotational angle of the radial movement lines 16V- 22C to 16VI 22C of the welding torch from the rectilinear movement section 16III- 16V up to the corner MW of the welding line 16, and said angle 0 is equal to 40, in the illustrated case.

In FIG. 3, reference symbol 1% represents the angle formed between the axis of the welding torch 12 and the bottom plate 5 of thework 4, and said angleis preset at 0 45, in the illustrated example.

Since the embodiment illustrated in FIGS. 2 and 3 is constructed as described above, starting from the state where the tip end of the welding torch 12 is directed to the corner 16I of the welding line 16 and the wire directed position is preset at l= 1.5 2 mm, the welding torch 12 is rotated in the clockwise direction about the cross point 22A between said loci 22 of the pivotal position, and simultaneously therewith said welding torch 12 is moved towards the center of rotation 22A along the radial movement lines 16I 22A, 16]] 22A and l6lII 22A, respectively, of the welding torch, whereby welding can be carried 'out over the welding region 16] to l6lII while maintaining the wire directed position I constant.

Then, after the welding torch 12 has reached the welding position 16V, the welding torch 12 is again rotated in the clockwise direction about the cross point 22C, and simultaneously therewith the welding torch 12 is moved towards the welding line 16 along the radial movement lines 16V 22C and 16Vl 22C, respectively, of the welding torch, whereby welding can while maintaining the wire directedposition l constant.

Further in the welding region 16V] to 16VII, by repeating the same operation as conducted in said welding region 16I.to l6lII, fillet welding can be carried out in a similar manner.

As described, according to the embodiment illustrated in FIGS. 2 and 3, welding can be carried out continuously not only in the rectilinear movement section l6lII to 16V but also in the sections 16] to l6lII and 16V to l6VI in the proximity of the corner 16] and 16VI, respectively, without interrupting the welding operation.

According to one modified embodiment of the present invention, in addition to the welding torch l2 disposed at the welding position 161, 'a second welding torch 12 can be provided in such manner that a radial movement line 16X 22A for the second welding torch is preset at an angle of 0 with respect to the radial movement line 161 22A of said welding torch l2 and the axis of said second welding torch is directed at a preset angle of 6 with respect to said radial movement line 16X 22A. If the driving means for the welding torches 12 and 12' are divided into upper and lower sections, or if the driving means are separated so as not to be extended up to the point 22A, then it is possible to make use of the two welding torches l2 and 12' simultaneously for carrying out two kinds of welding works simultaneously.

Furthermore, three or more welding torches can be simultaneously utilized in accordance with the invention.

The Apparatus Reference numeral 1 designates a travelling truck, which is supported on a bottom plate 5 of a lattice form of structure 4 by the intermediary of a driving wheel 2 and a freely rotatable caster 3. For stability, more such wheels and/or casters may be provided.

As shown apparently in FIG. 9, the driving wheel 2 is inclined towards the side wall 6 relative to the direction of advance, so as to propell the device parallel to said side wall 6.

At the center of the bottom of the travelling truck there is provided a suction device 7, so that when the suction device 7 is actuated to lock to the bottom plate 5 of the lattice form of structure 4, the travelling truck can rotate about a point 0 in FIG. 7 which vertically aligns with the axis of the sucker device 7.

At the top of the travelling truck 1 is integrally disposed a guide member 8, and a generally square lattice profiling plate 9 is fitted around said guide member 8 so as to be freely rotatable about said point 0. At the four corners of the lattice profiling plate 9 there are rotatably mounted respective side wall surface profiling rollers 10 so as to be positioned at the respective apexes of a square having its center located at the point 0. The lattice profiling plate 9 may be integrally, releasably fixed to said guide member 8 by means of a locking device.

Said locking device, although not shown in the drawings, for instance, comprises apertures provided at uniform intervals on the lattice profiling plate 9, and a locking solenoid provided on the truck 1, having a shaft which engages or disengages with said apertures.

A limit switch (not shown) is projected from the truck which operates so as to disengage said shaft to the locking solenoid with said aperture when contacting with the surface of the next wall intersecting with the wall surface under operation. And when the locking so-' lenoid rotates by a certain angle together with the truck 1, the supply of electricty to the locking solenoid is interrupted, and the solenoid continues rotating with its shaft pressed against the lattice profiling plate by means of the spring provided therewith, and after having rotated by 90, the shaft of the locking solenoid engages with the next aperture on the lattice profiling plate.

In addition, a sleeve bearing in the form of a tubular cylinder 11 directed in a horizontal direction is integrally mounted on the travelling truck 1, a horizontal support portion ofa working head 12 such as, for example, a welding torch being slidably fitted in the cylinder 11. A pin 13 is integrally secured to the working head 12 and directed in a vertical direction being slidably fitted in a working head guide cam groove 14 that is formed integrally with said lattice profiling plate 9, and between said cylinder 11 and said pin 13 is provided a compression spring 15 that is fitted around a horizontal support portion of said working head 12.

The working head guide cam groove 14 is formed so as to conform to the locus of point B (FIG. 7) whichis located at a fixed distance k from point A along a segment of line A connecting the center of rotation (I and any arbitrary point A on the welding line 16 along the side wall surface 6 of the lattice form of structure 4 as shown by a single dot chain line BB in FIG. 7, so that when said travelling truck 1 and said working head .12 rotate about point 0, the tip end of the working head 12 may be moved along, always in parallel to an intersecting corner edge 16 between the bottom plate and the side wall surface 6.

Since the embodiment of the apparatus illustrated in FIGS. 5 and 6 is constructed as described above, as shown in FIG. 8, the travelling truck 1 located at position Pl within one lattice section of the lattice form of structure 4 is caused to travel by itself (e.g., by driving wheel 2) towards one of the side wall surfaces 6 of said lattice form of structure 4 up to position P2, the lattice profiling plate 9 being then caused to rotate until two adjacent ones of the side wall surface profiling rollers make contact with said one side wall surface 6, said travelling truck being also caused to rotate until said working head 12 is directed at a desired angle (e.g., the angle 6 of FIG. 2) to said one side wall surface 6 (the state shown at P3 in FIG. 8), and thereafter said travelling truck 1 is caused to travel along said one side wall surface 6 with said lattice profiling plate 9 being fixed to said guide member 8. Then the tip end of said working head 12 can move along the intersecting corner edge 16 between the bottom plate 5 and the side wall surface 6 of the lattice form of structure 4 to achieve the desired work such as fillet welding.

When the two side wall surface profiling rollers 10 on the front side in the direction of advance have made contact with another side wall surface 6 intersecting at a right angle with said one side wall surface 6 (at the position P4 in FIG. 8), the suction device 7 is actuated to fix the truck at this position and the guide member 8 is made free to rotate with respect to the profiling plate 9. At that time, as described above, said limit switch operates so as to disengage the shaft of the locking solenoid with the aperture on the lattice profiling plate 9, and the rotational moment due to the distance of eccentricity between the driving wheel 2 and the center (I of the truck 1 acts upon the travelling truck 1 and working head 12 integrally so that they may rotate about 0 by relative to the lattice profiling plate 9, and the shaft of the locking solenoid engages with the next aperture on the lattice profiling plate 9.

During this rotation about point 0 (which lies on the axis of the suction device 7), since the work head guide cam groove 14 is shaped as illustrated in FIG. 7, the tip end of the working head 12 moves along the intersecting corner edge 16 between the bottom plate 5 and said one side wall surface 6 of the lattice form of structure 4, and after arriving at the corner where said one side wall surface 6 intersects with another side wall surface 6, it changes the direction of an advance by 90, and thus it moves along the intersecting corner edge 16 be tween the bottom plate 5 and said another side wall surface.

After the travelling truck I and the working head 12 have completed the rotation of 90 at position P4 in FIG. 8, the actuation of the suction device 7 is interrupted, and said travelling truck 1 is caused to travel along said another side wall surface 6 with said lattice profiling plate 9 being integrally fixed to said guide member 8 (the state shown at P5 in FIG. 8). When they have reached the corner portion P6 where said other side wall surface 6 and still another sidewall surface 6 intersect with each other, they are caused to operate in a similar manner to the operation at position P4, and by repeating the above described series of operations the tip end of the working head 12 is caused to move along the entire inner periphery of one lattice section in the lattice form of structure 4, whereby the desired work such as fillet welding can be achieved.

While thecross point between the axis of said working head 12 and the lattice form of structure was positioned on the intersecting corner edge 16 between the bottom plate 5 and the side wall surface 6 of said lattice form of structure 4 inthe aforementioned embodiment, by changing the mounting position of the pin 13 with respect to working head 12 it is possible to displace the cross point between the axis of said working head 12 and the lattice form of structure 4 either to the side of the bottom plate 5 or to the side of the side wall surface 6, if desired. It is to be noted that such relative positioning of the cross point with respect to the intersecting corner edge 16 can be maintained constant not only during the rectilinear travelling of the travelling truck 1 but also during the rotation of the same.

While the working head guide cam groove 14 was integrally formed in the lattice profiling plate 9 according to the embodiment illustrated in FIGS. 5 and 6, in a modified embodiment illustrated in FIGS. 9 to 11, a cam plate 18 having the same shape as said working head guide cam groove 14 is rotatable mounted on said guide member 8 separately from the lattice profiling plate 9, an inner gear 19 provided along an inner periphery of said cam plate 18 is meshed with a gear 20, a tension spring 17 is provided as stretched in place of the compression spring 15, and the gear ratio between said inner gear 19 and the gear 20 as well as the rotational speed of the gear 20 are selected in such manner that during the rotation of the travelling truck 1 the cam plate 18 may be maintained at a fixed relative position with respect to said lattice profiling plate as shown in FIG. 11. Then the same function and advantage as those ofthe first embodiment illustrated in FIGS. 5 and 6 can be realized.

While the above-described embodiments are applicable to a rectangular lattice form of structure, even .in

the case that the lattice is of the shape of parallelogram,

the desired objects can be achieved by simulating the relative position between the pivots of said side wall surface profiling rollers 10 to the parallelogram.

While the present invention has been described above with reference toits preferred embodiments as applied to a welding process, it will be readily appreciated by those skilled in the art that the subject inventive concept can be equally applicable to an automatic proversing a workpiece with a working head as described hereinabove possesses each of the attributes set forth in the specification under the heading Summary of the Invention hereinbefore. Because the method for traversing a workpiece with a working head of the invention can be modified to some extent without departing from the principles of the invention as they have been outlined and explained in this specification, the present invention should be understood as encompassing all such modifications as are within the spirit and scope of the following claims.

We claim:

1. A process for performing a task with a work head on a workpiece along a line which proceeds through a corner, comprising:

aiming the work head at a predetermined angle toward said line at a point upstream of the corner and mounting the work head for movement along a path laterally spaced from the line by a fixed distance, said path having a corner equating to the corner of said line;

translating the work head along the path toward the corner of the line, maintaining the aim of the work head at continuously successive points'along the line until the corner of the path is reached; then simultaneously:

a. rotating the work head about said corner of the path so as to bear a like relation to said line downstream of said corner of the line as said work head bore to said line upstream of said corner of the line, and

b. indexing the work head radially with respect to said corner of the path to maintain constant the distance between the work head and the workpiece along said line while passing through the corner; and

translating the work head along the path downstream of the corner of the path, maintaining the aim of the work head at continuously successive points along the line. 

1. A process for performing a task with a work head on a workpiece along a line which proceeds through A corner, comprising: aiming the work head at a predetermined angle toward said line at a point upstream of the corner and mounting the work head for movement along a path laterally spaced from the line by a fixed distance, said path having a corner equating to the corner of said line; translating the work head along the path toward the corner of the line, maintaining the aim of the work head at continuously successive points along the line until the corner of the path is reached; then simultaneously: a. rotating the work head about said corner of the path so as to bear a like relation to said line downstream of said corner of the line as said work head bore to said line upstream of said corner of the line, and b. indexing the work head radially with respect to said corner of the path to maintain constant the distance between the work head and the workpiece along said line while passing through the corner; and translating the work head along the path downstream of the corner of the path, maintaining the aim of the work head at continuously successive points along the line. 